Conventional techniques for measuring current in high voltage motor or transformer circuits employ current transformers with output signals wired directly from the high voltage motor or transformer environment to the low voltage signal processing and control circuitry. In many of these applications the requirement for withstanding high electrical surges, i.e., 60 kV, and the requirement for electromagnetic interference immunity render the conventional current measuring and signal transmission techniques unacceptable. The development of fiber optic waveguide transmission and the present development of optical sensors affords a unique opportunity to enhance isolation between the high voltage and low voltage environments of a motor control or transformer circuit thus providing a current measuring and transmission capability suitable for meeting the safety and operational specifications for transformer and motor control systems.